The present invention disclosed herein relates to an apparatus for treating a substrate, and more particularly, to an apparatus for treating a substrate by using plasma.
Plasma is generated at very high temperature or by strong electric fields or radio frequency (RF) electromagnetic fields, and is denoted as an ionized gas state formed of ions, electrons, or radicals. In semiconductor device fabrication processes, an etching process is performed by using plasma. The etching process is performed by allowing ion particles contained in the plasma to collide with a substrate.
Antennas may apply high frequency power to a process gas to excite the process gas to a plasma state. Typical antennas have a fixed shape, and are bilaterally symmetrical. Theoretically, such an antenna generates plasma having a symmetrical density distribution along the radial direction of the antenna. However, a density distribution of plasma is practically asymmetrical due to various causes. Such an asymmetrical density distribution of plasma may cause an uneven substrate treating process.